|Title:||Recycling waste materials and dredged sediment by stabilization/solidification : optimizing the design mixture|
Hong Kong Polytechnic University -- Dissertations
|Department:||Faculty of Construction and Environment|
|Pages:||x, 77 leaves : col. ill. ; 30 cm.|
|Abstract:||In Hong Kong, 380 million of cubic meters of sediment are required to be dredged for the navigational maintenance of harbours and channels. This thesis is proposed to stabilize and solidify the contaminated sediment with recycled waste materials, including recycled sea shells (food waste), coal fly ash (CFA), recycled concrete aggregate (RA), crushed glass (CG), coal bottom ash (CBA), and municipal waste incinerator bottom ash (MIBA). They are partial used as substitutes of binders and fine/coarse aggregates, to produce non-loading concrete blocks. The effectiveness of stabilization/solidification (S/S) was assessed in terms of compressive strength and (toxicity characteristic leaching procedure) TCLP leachability, according to the engineering standards for non-loading concrete blocks and site formation/landfill disposal. In addition, microstructure, elemental analysis, crystalline structure, pore structure and pore-size distribution of S/S blocks were analyzed by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy detector (EDX), X-ray diffractometer (XRD) and mercury intrusion porosimetry (MIP), respectively. The experimental results showed that if the binder to aggregate ratio was kept at 1:4, and 25% of aggregate was replaced by sediment, the compressive strength of S/S samples were able to fulfil for non-loading bearing (4.14 MPa) (ASTM, 2011) and TCLP results of S/S samples would meet the leaching limitation (USEPA, 1992). Besides, ordinary Portland cement (OPC) could be replaced by CFA and lime with negligible effect at low replacement level (33.3%). In addition, it was found that RA, CG, CBA and MIBA can be effectively used as coarse aggregate. Moreover, the addition of 1% CaCl₂, Na₂CO₃ and FeCl₃ as additive or ground granulated blast slag (GGBS), Metkaolin (MK) and glass wool as fillers into the mixture showed a favourable effect, and the maximum increasing of compressive strength was 7%. On the whole, the results had demonstrated that contaminated sediment could be treated, processed by S/S, and reused for making non-loading blocks with a safe property.|
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